1. FIELD
The embodiments discussed herein are directed to a semiconductor memory and an electronic device and, more particularly, to a semiconductor memory and electronic device for exercising sequence control.
2. DESCRIPTION Of The RELATED ART
A reduction in the power consumption of portable devices, such as portable telephones, is required for the purpose of increasing the length of use time, wait time, or the like.
In recent years the capacity of memory cell arrays included especially in portable devices has increased rapidly. In addition, increases in gate leakage currents and channel leakage currents have taken place because of the miniaturization of large-scale integration (LSI). These leakage currents are not negligible. This contributes to an increase in power consumption. Power consumption tends to increase further in future.
The following measure is proposed as a method for solving this problem. When there is no need to hold information in a memory cell array, power is turned off. For example, power is turned off at power save time, such as intermittent receiving time or nonuse time. When it is necessary to hold the information in the memory cell array, power down is performed by, for example, decreasing voltage (see, for example, Japanese Patent Laid-Open Publication No. Hei11-297071).
However, if a microprocessor is used for controlling the above power down, complex control must be exercised because of, for example, a delay which occurs at the time of turned on/off a switch. This greatly impedes a reduction in power consumption.